Perfusion Limitation vs Diffusion Limitation - Respiratory Physiology

KEY POINTS:Presentation 24-72h post-injury - risk during major trauma and surgery (esp long bones)Pathophysiology:Fat from marrow into lungs = pulmonary hypertension, RV strain, hypoxiaSIRS from fatty acids = myocardial depression, ARDS, DICPrevention = early immobilisation/reduction and operative managementDx of exclusion but classic triad of GURDS = confusion, respiratory distress and petechiaePetechiae only present in 50% but pathognomonic Mx = exclude other Dx (PE, anaphylaxis) --> treat fracture (no cement)A) ETT (req in 40%)B) FiO2 1.0, ARDS-ventilationC) fluids, pressors, inotropes, coags correct (DIC)D/E) normal sugar/tempICU post-op, resolves <7 days

Explain the cardiovascular effects of central neuraxial blockade2019B08 62.6%2013C12 56.0%2013A12 38.0%

Explain the effects of intermittent positive pressure ventilation on cardiac output 2021B01 56.5% 2019A01 54.7% 2014A05 37.6% 2013B01 19.7%

What is the normal value for PVR? Outline physiological factors influencing PVR.

Discuss the potential adverse effects of suxamethonium. Describe how suxamethonium and non-depolarising neuromuscular blocking agents produce their adverse cardiovascular effects. Outline the possible reasons for prolonged paralysis induced by an intravenous dose of 1 mg/kg of suxamethonium.

Pharmacology - Dose, Onset (Mechanism of Action - Accommodation, Phase II Block), Offset, Side Effect (Summary) Describe how suxamethonium produces neuromuscular blockade. What is the mechanism of recovery of neuromuscular function and what mechanisms may be involved in Phase II block?

Describe the factors influencing CO2 tension in blood.

Outline the central nervous system effects of an awake person breathing air containing CO2.

Explain the difference between perfusion limitation and diffusion imitation in the transfer of gas between alveolus and pulmonary capillary. Outline the factors that determine whether a gas is perfusion or diffusion limited.

Briefly outline the differences between the pulmonary circulation and the systemic circulation.